This invention relates to self-leveling systems and more particularly to a refrigerator cabinet support that will maintain the cabinet level on a surface that is slanted, unlevel, or out-of-flat in such a way that there is equal weight distributed at the two front corners.
It is highly desirable that appliances generally be provided with adjusting means to insure that all four support feet are firmly positioned on the floor and the appliance level on the floor even when the floor or surface itself is unlevel or out-of-flat.
Frequently, appliances such as washing machines and refrigerators, are placed on sloping surfaces. Usually, manually adjustable supports are affixed to the front underside of the cabinets of the appliances. These supports are individually adjustable so that they can be employed for compensating for slope in a supporting surface from front to back and also for slope from side to side. The front supports, usually two in number, must often be adjusted to unequal lengths to compensate for the side-to-side slope in the supporting surface. Where the cabinet has two fixed rear supports, the cabinet may then rock on three of its four supports. In the case of an appliance such as a washing machine, this may result in undesirable "walking." Of potentially greater concern, the weight of the cabinet may cause twisting of the cabinet to bring all four supports into engagement with the supporting surface. This is particularly of concern in a refrigerator cabinet for it is very heavy when a normal amount of food is stored therein. Because a refrigerator cabinet is tall and not as rigid as more compact cabinets, it has a greater tendency to twist when not supported on all of the supporting elements. This twisting action of the cabinet may cause distortion of the front face of the cabinet against which the door closes and thereby prevent the door from properly sealing its gasket with respect to this front face of the cabinet. Without proper sealing, heat will leak into the refrigerator's cooling compartment and result in inefficient refrigeration and waste of electrical energy. Moreover, in the case of refrigerator-freezers which have two doors, either one above the other or side by side, this twisting may prevent the doors from lining up well enough to be aesthetically acceptable.
Since the above-mentioned appliances are heavy and are often placed in confined areas, it is difficult or impossible to provide access to the rear supports for adjusting such supports to compensate for a sloping surface, particularly one which slopes from side to side. Hence, it is important to provide a means for effecting automatic adjustment of a rear support of the cabinet of the appliance to conform to the adjustment of the front supports in order that the cabinet may be uniformly supported, front and back, in an upright position, and to do this without requiring access to the rear supports.
The problem of providing self-adjusting supports for facilitating the leveling of appliances such as refrigerators and washing machines when such appliances are positioned on sloping floor surfaces is well-known, and the prior art discloses many examples of self-adjusting assemblies adapted especially for facilitating the leveling of such appliances without requiring access to the rear support structure and without requiring the use of manual procedures or tools. For example, U.S. Pat. No. 3,954,241 teaches a self-adjusting assembly especially adapted for facilitating the leveling of an appliance, such as a washing machine or the like, on a sloping floor in order that the appliance be firmly positioned thereon. The assembly includes a pair of brackets located at the two rearmost, lower corners of an appliance, and a flexible cable element extending from one bracket to the other. Each bracket is provided with an independently adjustable leg member, with the members being interconnected by the cable. If both rear legs do not engage the floor, the leg which first engages the floor is forced upwardly by the weight of the cabinet. Through the cable, this causes a corresponding downward movement of the other leg until it is brought into engagement with the floor.
Another example of a support with automatic adjustment is taught by U.S. Pat. No. 3,880,388. The support is of the leg-type, comprising two vertically movable legs coupled together, in one embodiment, by a chain of rigid thrust elements encased by a tubular guide. These elements are arranged such that as the weight of the supported structure causes one leg, which engages the surface upon which the structure is placed, to move upwardly, the other leg is urged downwardly until it engages the surface.
Still another example of a support with automatic adjustment is taught by the U.S. Pat. No. 2,695,147. The support includes a pair of cams at the rearmost corners of an appliance, which cams are connected together by a connecting rod. The cams are shaped to slope in opposite directions and are arranged for rotation about vertical axes. The cams are rotatably connected to plungers which support the cams, the plungers forming feet or legs which actually support the appliance on a floor or other surface. If greater pressure is applied to one of the plungers than is applied to the other, the cam in engagement with the plunger having the greater pressure applied thereto tends to rotate about a vertical axis so as to shorten that plunger relative to the base of the appliance. This rotation is transmitted through the connecting rod to the other cam and causes rotation of this other cam in a corresponding direction, but, because of the opposite slope of the cams, this tends to lengthen the plunger connected thereto relative to the base. This produces an equalizing action that automatically provides uniform support for the appliance on the supporting surface.
In lieu of leg-type supports, some prior art cabinet structures employ a single, rear roller-type support in combination with two adjustable front supports. If a single roller-type support is utilized, it is necessary to provide a roller of reasonable length to assure adequate stability of the rear portion of a cabinet. This is especially important where the supporting surface is a soft floor covering. If the weight of the rear portion of the cabinet is supported on a short roller, this may result in a substantial depression in the supporting surface. Such depression, aside from marring the appearance of the floor covering, would hinder the moving of the appliance from the confined space. However, where the two front supports are adjusted to unequal lengths on a floor which slopes from side to side and a roller of adequate length is employed, another problem is encountered in that one end of the rear roller may engage the floor covering and tend to press into the soft floor covering. A U.S. Pat. No. 4,102,556-William M. Webb is directed to this particular problem.
Some prior art cabinet structures, for example, that shown in U.S. Pat. No. 3,222,021 employ a mechanism comprising two oppositely sloped ramps in lieu of leg-type supports. The ramps are formed at the two rear corners of a cabinet and the cabinet is supported on these ramps in such a manner that a slight sideward movement of the cabinet results in one rear corner sliding up one ramp and the other rear corner sliding the same distance down the opposite ramp. The ramp construction provides substantial resistance to movement at the rear corners. This ramp-type support is frequently utilized with washing machines because washing machines usually shake while spin drying, and the friction of the ramp is quite helpful in preventing unwanted rocking while being easily overcome for automatic adjustment during a spin cycle. However, since refrigerators shake very little and since refrigerator cabinets are tall and not as rigid as more compact cabinets, such as washing machine cabinets, and, therefore, have a greater tendency to twist, the rear support should be able to adjust with very little frictional resistance. Hence, the ramp-type support, with its substantial friction, is not particularly useful in supporting refrigerator cabinets on surfaces which slope from side to side.
One example of which the present invention is an improvement is U.S. Pat. No. 2,540,750-Morrison issued Feb. 6, 1951, wherein automatically adjustable legs are mounted on bearings attached to the appliance to permit vertical movement relative thereto. Cranks, each having a horizontally disposed arm bearing on the top of one of the legs and a vertically disposed arm extending downwardly, are pivotally supported from the appliance. A bar is pivotally attached to the two downwardly extending crank arms to cause each crank to urge its corresponding leg downwardly with like force. The bar is tensioned by increased load and when the appliance is placed upon an uneven or tilted supporting surface, the legs move up and down until the forces supported by each are equal.
One problem with such prior art self-adjusting leg-type support is that the mechanisms employed are of expensive and complex construction due to the use of many parts and to the functional relationships of these parts.
By this invention, these disadvantages and limitations of the prior art are overcome, and a support for cabinets, such as refrigerators and washing machines, is provided which is simple in construction, which can be manufactured economically and which readily and automatically adjusts itself for uniformly supporting the cabinet on a surface which slopes from side to side.
Accordingly, it is an object of this invention to provide an improved construction of a rear support structure for a cabinet which automatically adjusts itself to a supporting surface sloping from side to side.
It is another object of this invention to provide such a rear support structure which proportionately distributes the weight of the rear of the cabinet to insure that all four corners of the cabinet will be uniformly supported on the supporting surface to prevent any rocking or twisting.